JPH0251807A - Manufacture of nb3al superconducting wire rod with extremely fine multiplex structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for manufacturing an Nb3Al superconducting wire having an ultrafine multiple structure. There are more details.

(Conventional technology and its problems) Wires exhibiting superconducting properties that are exposed to strong magnetic fields and alternating magnetic fields can be used in NMR analyzers, nuclear fusion reactors, energy storage, electromagnetic propulsion ships, superconducting power generation, or superconducting It is advantageously used in transformers and the like.

Superconducting wires made of Nb, sn, and V3Ga are known as superconducting wires for strong magnetic fields that are expected to be used in these five fields, but these wires have several serious drawbacks. Therefore, there are still many difficulties in providing practical service.

That is, the upper critical magnetic field of these Nb, sn, and VIGm wires is only about 20 T, which is not practically satisfactory. In addition, this wire rod is made of copper alloy (Cu-S
There is a problem in that the critical temperature and upper critical magnetic field will decrease unless it is generated at a high temperature with n, or Cu-G,). Moreover, when generated at such high temperatures, Nb3
There is a problem that the crystal grains of Al become coarser, which lowers the critical current density.

In addition, this Nb3Al superconducting material has a high critical temperature and high upper critical magnetic field, which is advantageous for practical use, and it has been difficult to make it into a wire rod. Laboratory level Compared to these wires, Nb3Al-based superconducting material has a higher critical temperature ('rc) and an excellent upper critical temperature of 30T, and is expected to be a promising superconducting wire material for practical use. be.

However, the characteristics of this Nb3Al are Nb1Sn
Although it is much better than 'V s G a,
Those with excellent stoichiometric composition are unstable at low temperatures, and above 150'0'C.For example, as a manufacturing method for this Nb, Al wire, one that utilizes a diffusion reaction is a promising method. It is believed that. Specifically, this method includes a powder metallurgy method, a jelly roll method, an infiltration method, and an a & knife method. The powder metallurgy method is shown in Figure 2 (a).
As shown in Figure 3, a composite (1) consisting of Nb powder (B) filled in a Nb pipe (A) and A1 or A1 alloy powder (X) is cold-worked to create an extremely thin Nb/Al multilayer structure. The composite wire is then processed and then heat treated at a relatively low temperature of 750 to 1100°C to diffuse and generate Nb3Al to form a Nb-Al@ material. The jelly roll method uses a composite (1) in which Nb foil (O) and AI or A1 alloy foil (T) are overlapped and rolled up as shown in Figure 2(b).
) is similarly fζ-processed and treated.
Only the same characteristics as m-wire can be obtained.

If heat treatment is performed at high temperature in an attempt to eliminate this drawback, it is impossible to obtain l'Jb, Al wire with similarly excellent superelectric properties.

As described above, Nb and Al wires have a problem regarding the relationship between heat treatment temperature and characteristics that must be overcome in order to put them into practical use.

This invention was made in view of these circumstances.

However, Nb, Al obtained by these methods
Although the wire rod has a relatively good critical current density in a low magnetic field due to its fine metal structure, the upper critical magnetic field deviates from the stoichiometric composition because it is heat-treated at a low temperature to generate Nb3Al. It is easy to generate from Nb3Al with low
The purpose of this invention is to provide a new manufacturing method that can easily produce 1chH of Sn or wire.

(Means for Solving the Problems) In order to solve the above problems, the present invention disposes a composite consisting of aluminum or an aluminum alloy and a niobium base material in a metal or alloy matrix material, and Nb3Al with an ultra-fine multi-layered structure characterized by cold working and forming into a wire into a composite wire with a diameter or thickness of 0.5 J m or less of aluminum or aluminum alloy, and then subjecting it to high-temperature heat treatment for a short time of 10 seconds or less. Provides a method for manufacturing superconducting wire.

This invention also provides Nb and Al obtained by this method.
The present invention also provides a method for additionally heat-treating the wire at a temperature of 600 to 800°C.

As mentioned above, this surface forming method can be carried out by continuously heating and cooling the cold-worked composite. Heating and cooling can be performed in an inert gas atmosphere or in a liquefied inert gas.

Of course, this is not limited to the above (for example, the cooling can also be performed continuously using a water-cooled copper reel or the like).

When using aluminum alloy, 15. This is based on the knowledge discovered for the first time through verification that Mg is less than 1% and z''s is less than 1%.

The high temperature heat treatment in this case is 7
The temperature increase of 50 to 1100°C is performed under conditions of high temperature, preferably about 1400°C or higher, and is performed under conditions such as direct current heating of Nb/At double metal wire, mη expansion, or width vs. heating. etc.・N b / A 1
Ge may be contained in a total ratio of 4at96 or less without moving the composite wire.If the composition is within this range, the ffi of Nb and Al wires may be
It does not adversely affect the conductive properties. Its processing properties are similar to niobium.

As the niobium base material, niobium or a niobium alloy containing 4 at% or less of 81 and Qe in total as described above can be used.

As an IJTx material for further recompositing a composite material consisting of aluminum or aluminum alloy and a niobium base material, a material with a melting point of 2000°C or higher that does not easily or does not react with the niobium base material is used. It is preferable to use niobium, tantalum, vanadium, tungsten, molybdenum, titanium, zirconium, or an alloy thereof to obtain a conductive wire. In this case, an additional 600 to 80
Additional heat treatment at 0° C. improves the crystalline order of Nb3Al and further improves the high-field properties.

When using pure aluminum, the so-called composite processing method becomes difficult, so the powder method, jelly roll method,
Alternatively, it is preferred to use an infiltration method.

In either case, aluminum or aluminum processing is used. At this time, the diameter or thickness of the aluminum or aluminum alloy in the composite wire is reduced to 0.51 mm or less by this processing. This point is also one of the features of this invention.0 It is possible to extremely reduce the AC loss of Nb3Al superconducting wire with excellent strong magnetic field characteristics by heating and cooling it to a high temperature in a short time of 10 seconds or less. Combined processing methods are particularly advantageous.

In the manufacturing method of this invention, a metal or alloy is used as the matrix material, but if this is not used, the N'b3Al filaments will electrically contact each other and the diameter will be equivalent to a huge filament. In addition, in this invention, if oxygen-free steel or pure aluminum is further composited, the electromagnetic stability of the superconducting wire becomes Further improvement.

Figure 1 shows the main parts of the manufacturing method of this invention as described above.
The Nb/Al composite (1) produced by the conventionally known composite processing method, powder metallurgy method, jelly roll method, and infiltration method shown in d) was processed into a 1.14 m line. 110 of these single-core composite wires were bundled and inserted into a niobium vibrator with an outer diameter of 20 m and an inner diameter of 14 yen to create a multiplex composite, which was then subjected to cold wire drawing. Processed into. This 110-core compound I gland is exposed (this 11
The process of wire-drawing the multiplex composite, which was bundled and inserted into a niobium vibe, was repeated twice, and the outer diameter was 0.3 to 10.
Intestinal 110

(Example) Example 1 A round bar of A1-61t%Mg with an outer diameter of 6W was inserted into a niobium vibe with an outer diameter of 12 mm and an inner diameter of 6 mm to prepare a composite.
The outer diameter was generated by cold wire drawing such as groove rolling, swaging, or drawing. Core diameter is 0.5
We manufactured duplex wire rods with a diameter of less than μm. The superconducting critical temperature (TC) and critical current degree (Jc) of each wire were measured. Table 1 shows the results.

When the core diameter was 0.3 μm or less, a high Tc of 17 or more was obtained when the total energy applied during heating was about 100 KJ/cd. Further, when the wire rod was subjected to additional heat treatment for several days at around 700°C, it exhibited a high Tc of 18 or more. In addition, Jc depends on the core diameter, and unless the core diameter is 0.3 μm or less, Jc will be higher than 10"A/d (4, 2,
l0T) was not obtained. Samples with T C > 18 are H
ct(4,2K)>30T.

These wires have extremely high superconducting properties,
Furthermore, after additional heat treatment on these superconducting wires, those plated with copper are electromagnetically extremely stable. %MQa+%2Q at%L at%Ag.

ayuCu.

a+%M g -5 1Q at% Mg.

5　m1%Zn.

5 at% Ll.

4 at%Ag, at%Cu.

11% Zn.

A composite body is prepared by inserting the wire into a niobium pipe with an inner diameter of 6mm, and then cold wire drawing processing such as groove rolling, swaging, or drawing is performed to reduce the outer diameter to 1.14JE16.
Processed into lines. 110 of these single-core composite wires were bundled and inserted into a tantalum pipe with an outer diameter of 20mm and an inner diameter of 14mm to create a multilayer composite.
It was processed into a 4m 110-core composite wire. This 110-core composite suspension has a structure in which 110 alloy filament is further inserted.
An ultra-fine multifilamentary wire with a core diameter of 5 μm or less is made to allow direct threading.
M, 71D heat treatment was performed for a short time of 10 seconds or less. Then, when additional heat treatment was performed at 700°C, Tc of 17 or more and HC of 30T or more! , 1 × 10' A /
A J c (4,2, 10 T) greater than cd was obtained.

Example 3 An Al-5a 1% Mg round rod with an outer diameter of 6 mm was heat-treated by directly applying electricity in nitrogen with an outer diameter of 12 mm, and was heated and cooled for 0.2 seconds while moving the rod in a straight line. produced a filament.

After additional heat treatment at 700℃, superconducting critical temperature (TC
), and the critical current density (Jc) was measured. In this example, the results were almost the same as in Example 1 using a niobium pipe. We also have vanadium pipes, tank steel pipes,
Even when molybdenum pipes, titanium pipes, and zirconium pipes were substituted, there was almost no change in the ultra-IC conductivity characteristics.

Example 4 Aluminum powder and niobium powder were mixed and filled into a niobium pipe with an outer diameter of 301B and an inner diameter of 20111B, and grooved roll processing was performed.
The wire was processed into a wire with an outer diameter of 0.3 m by cold wire drawing such as swaging or drawing. In the same manner as in Example 1, this wire was filled into a niobium pipe in liquid nitrogen and processed into a wire with an outer diameter of 0.39 by cold wire drawing such as groove rolling, swaging, or drawing. This wire was heat-treated in the same manner as in Example 1 by directly applying current in liquid nitrogen while moving the wire to heat and cool for 0.2 seconds, thereby generating Nb3Al filaments within the wire. After additional heat treatment at 700° C., the superconducting critical temperature (Te) and critical current density (Jc) were measured. In this example as well, the results were almost the same as in Example 1. Also, instead of aluminum powder, Al-3at%M
g, Al-2aj%Mg-1a1%S1 and Al-3
Almost the same superconductivity was obtained even when at%Ag powder was used.

Example 5 Aluminum foil with a thickness of 1 oam and niobium foil with a thickness of 40 μm were overlapped and rolled to form an outer diameter of 30 wk and an inner diameter of 2018 mm.

Implementation - @ 6 A composite made by pressing niobium powder and sintering it in a vacuum at 2200°C into a porous body impregnated with molten aluminum was filled into a niobium pipe with an outer diameter of 30 mm and an inner diameter of 20 mm. The wire was processed into a wire with an outer diameter of 0.3 mm by cold wire drawing such as groove roll processing, swaging processing, or drawing processing. This wire was directly energized in liquid nitrogen in the same manner as in Example 1,
The heat treatment was performed while moving the sample so that heating and cooling occurred for 0.2 seconds. Nb3Al filaments were generated within the wire. After additional heat treatment at 700℃, the superconducting critical temperature (
Tc) and critical current density (JC) were measured. Even if this column was changed, the results were almost the same as in Example 1. Also, instead of molten aluminum, molten Al-381% M g s A
+ -J at%Ag and A]-3, it has a large critical current density, which is extremely important in practice, and has excellent superconducting properties with a high critical temperature and high upper critical magnetic field. Furthermore, it is also possible to manufacture a wire having an ultrafine multicore structure that has extremely low AC loss and can be used for AC at commercial frequencies. These have made it possible to realize superconducting magnets that can generate even stronger magnetic fields, expanding the applications of AC superconductivity, and creating high magnetic fields and '9. Various embodiments are possible with respect to details such as the shape and size of the current superconductor tube, the shape and size of the aluminum foil and niobium foil, and the cold working method and heat treatment method.

(Effects of the Invention) As has been explained in detail above, the present invention makes it possible to easily produce Nb and Al wire rods at temperatures as low as 0.degree. C., which has been difficult in the past. The Nb, Al wire rod obtained by this invention has an extremely fine metal structure and a thick margin (which is advantageous).

Furthermore, in the manufacturing method of the present invention, since intermediate annealing is hardly required, the wire manufacturing cost can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the Nb/Al multiplex composite according to the present invention. 1...Nb/Al composite 2...Matrix material 3...Nb/A + multiple composite Figure 2 (,)(
b), (C), and (d) are cross-sectional views showing an Nb/A1 composite in a conventional method for producing an Nb3Al wire. A... Niobium vibrator... Niobium powder... Aluminum or aluminum alloy finishing... N b / A 1 multiple composite O... Niobium foil strength... Aluminum or aluminum alloy foil...・Niobium sintered body...infiltrated aluminum or aluminum alloy...niobium...aluminum alloy h1 (,) Powder metallurgy method (b) Jelly roll method (c) Infiltration method (d) Combined processing method ( a) Engineering (C) (-m-to 1111) (d)

Claims (14)

[Claims] (1) A composite consisting of aluminum or aluminum alloy and a niobium base material is placed in a matrix material of metal or alloy, and this is made into a wire rod by cold working, so that the diameter or thickness of aluminum or aluminum alloy is 0.5 μm.
Nb_3Al with an ultra-fine multi-layered structure, which is made into a composite wire with a diameter of less than m and is subjected to high-temperature heat treatment for a short time of less than 10 seconds.
Manufacturing method of superconducting wire. (2) Claim of high temperature heat treatment at a temperature of 1400°C or higher (
3) The method for producing the Nb_3Al superconducting wire having the ultra-fine multiple structure. (3) The method for producing a Nb_3Al superconducting wire having an ultrafine multiple structure according to claim (3), wherein the Nb_3Al superconducting wire is subjected to high-temperature heat treatment by direct current heating or induction heating. (4) Nb_3A having an ultrafine multiple structure according to claim (1), wherein the composite wire is continuously heated and cooled while moving.
l Superconducting wire manufacturing method. (5) The method for producing a Nb_3Al superconducting wire having an ultrafine multiple structure according to claim (1), wherein heating and cooling are performed in an inert gas atmosphere and/or a liquefied inert gas. (6) Aluminum alloy contains 15 at% or less Mg, 10
A total of 0.5 to 1 at% of Zn, 10 at% or less of Li, 8 at% or less of Ag, and 5 at% or less of Cu.
5 at % of the Nb_3Al superconducting wire having an ultrafine multiple structure according to claim 1. (7) The method for producing a Nb_3Al superconducting wire having an ultrafine multiple structure according to claim (6), wherein the aluminum alloy further contains Si and Ge in a total of 4 at% or less. (8) The method for producing a Nb_3Al superconducting wire having an ultrafine multiple structure according to claim (3), wherein the niobium base material is made of a niobium alloy containing 4 at% or less of Si and Ge in total. (9) The method for producing a Nb_3Al superconducting wire having an ultrafine multiple structure according to (1), wherein the composite wire is further stabilized by compounding oxygen-free steel or high-purity aluminum on the outside or inside of the composite wire. (10) Nb_3A having an ultrafine multiple structure according to claim (1), wherein the composite material comprises an aluminum alloy core and a niobium base material.
l Superconducting wire manufacturing method. (11) Nb_3A having an ultrafine multiple structure according to claim (1), wherein the composite material is formed by pressing a mixture of aluminum or aluminum alloy powder and niobium powder.
l Superconducting wire manufacturing method. (12) Claim (1) in which the composite material is formed by wrapping aluminum or aluminum alloy foil and niobium foil in a layered manner.
A method for manufacturing the Nb_3Al superconducting wire having the ultrafine multiple structure described above. (13) Claim (1) wherein the matrix material is a composite in which aluminum or aluminum alloy is melted and infiltrated into a porous body made by sintering niobium powder or niobium wire.
) A method for producing a Nb_3Al superconducting wire having an ultrafine multiple structure. (14) The method for producing a Nb_3Al superconducting wire having an ultrafine multiple structure according to claim (1), further comprising additional heat treatment at a temperature of 600 to 800°C.